The present invention relates to a semiconductor device. In particular, the present invention is suitable for use, for example, in a semiconductor device including a metal insulator semiconductor field effect transistor (MISFET) of vertical type.
Power devices represented by a field effect transistor (FET) with high operating voltage that allows a large current to flow, or a so-called power transistor, are widely used in power supply for information equipment, home appliances, vehicle mounted equipment, and the like, as well as used in motor drive devices. The power transistors for such applications are required to reduce the ON resistance.
A trench gate type vertical MISFET is known as a power transistor. The trench gate type vertical MISFET is a device in which a metal insulator semiconductor (MIS) structure is formed in a groove, or a trench, formed in a semiconductor substrate in which current flows in the thickness direction of the semiconductor substrate. Further, there is a technique for reducing the ON resistance by using the trench gate type vertical MISFET having a super junction structure. The super junction structure is a structure formed in the drift layer of a vertical MISFET, in which a columnar semiconductor region having a polarity opposite to that of the drift layer is formed. Such a structure can contribute to an increase in the source-drain breakdown voltage. As a result, it is possible to improve the trade-off between the reduction in the ON resistance and the improvement of the source-drain breakdown voltage.
Japanese Unexamined Patent Application Publications (Translation of PCT Applications) No. 2013-503491 (Patent Document 1) and No. 2013-503492 (Patent Document 2) disclose a technique of having first and second columns of type 1 dopant as well as a column of type 2 dopant in a super-junction trench power metal oxide semiconductor field effect transistor device.